$\begin{align} & Men : days \\[5pt] & 5 : 4\\[5pt] & 4 : x\\[5pt] & 5\times 4 = 4x\\[5pt] & \frac{20}{4} = x\\[5pt] & x = 5 day\\[5pt] \end{align}$
	$\begin{align} & Men : days : hours \\[5pt] & 9 : 4 : 5 = 180\\[5pt] & x : 10 : 6 = 60x\\[5pt] & 180 = 60x\\[5pt] & x = 3 Men\\[5pt] \end{align}$
	$\begin{align} & Men : days \\[5pt] & 18 : 6 = 108\times 2 = 216\\[5pt] & x : 9 = 9x\\[5pt] & 216 = 9x\\[5pt] & x =24 Men\\[5pt] \end{align}$

By studying this lesson you will be able to

Solve problems related to inverse proportions.